Combination electrical control assembly



Sept.- 23, 1941.

N. C. SCHELLENGER COMBINATION ELECTRICAL CONTROL ASSEMBLY Filed Feb. 2,1959 l INT/v ENT OR. fyi/mfom Ccel@ef B 5 I A'ITOWEYS Patented Sept. 23,1941 COMBINATION ELECTRICAL CONTROL ASSEBIBLY Newton C. Schellenger, ElPaso, Tex., assignor to Chicago Telephone Supply Company, Elkhart, Ind.,a corporation of Indiana Application February 2, 1939, Serial No.254,318

(ci. 2in- 48) 7 Claims.

This invention relates to a new and improved combination electricalcontrol assembly and more particularly to such an assembly where theunits are closely associated and connected for joint operation.

In one specific form the assembly comprises a variable resistance as oneunit and an associated switch as the second unit. Assemblies of thischararacter are in wide general use in radio receivers and transmitters,public address systems, test apparatus and the like. In manyapplications of such units the switch and variable resistance areconnected in different parts of the circuits involved and anyelectrostatic, electromagnetic or capacity coupling between the parts isundesirable. Specic examples are where such combination assemblies Vareused in radios or audio amplifiers with the switch controlling thealternating current input to the apparatus and the variable resistanceconnected as a volume control in some portion of the circuit after whichthere is substantial audio amplification. In such cases an alternatingcurrent hum from the switch may be picked up by the variable resistanceand amplied to such an extent as to be highly objectionable.

Combined assemblies have in the past been made with a metallic shieldlocated between the units and with a switch operating cam extendingthrough an opening in the shield. In such devices, where the cam is `notconnected into either electrical circuit and where the current carryingportions of the switch are located to one side of the opening, suicientshielding effect is alforded for many applications of such devices.

With the more compact assembly of parts now customary in the radio andother fields using devices of this character, parts are so closelyplaced that very eficient shielding is often required. It is oftennecessary not only to shield the switch from the associated control unitbut also to shield the switch and sometimes the second unit fromadjacent parts such as unshielded tubes or coils.

It is an object of the present invention to provide a new and improvedcombination electrical control assembly.

It is an additional object to provide an assembly of this characterwhere a plurality of units are connected for joint operation.

It is also an object to provide such an assembly in which there iseffective shielding between units of the assembly by a xed imperforateshield member interposed therebetween.

It is a further object to provide an essembly which is compact andsimple in design and construction and adapted for commercial production.

Other and .further objects will appear as the description proceeds.

I have shown certain preferred embodiments of my invention in theaccompanying drawing, in which- Figure 1 is an elevation of thecombination control with portions broken away;

Figure 2 is a section taken on line 2-2 of Figure l;

Figure 3 is a perspective view of the operating member; and

Figure 4 is a plan view, on a reduced scale, showing the switch cover.

The combination electrical control shown, comprises a first unit havinga base I I formed of insulating material and having a metallic housingI2 secured to the base and enclosing the mechanism of the unit. In theform of construction shown, this unit is a variable resistance similarto that shown in my prior application, Serial No. 218,062, led July 8,1938. The

, unit includes a metallic thimble I3 secured to therewith.

The details of construction of the variable resistance unit form no partof the present invention. It may be briefly stated that the unitincludes a movable contact member II driven by the arm I5 and engaging aresistance strip not shown. The contact member Il also makes contactwith the collector ring I8 which is connected to one of the terminalsI9. 'I'he other terminal 2G may be connected to an end of the resistancestrip. The device may include a third terminal connected to the oiisetend of the resistance strip which terminal would be in the rear ofterminal 2li, as seen in Figure l. It is to be noted that the base I Iis generally circular in shape, but is provided with an extended portion2| to which the terminal lugs I9 and 2l] are secured, The metallichousing I2 carries around the inner side of its cylindrical face aninsulation strip 22 which insulates the housing Y from the portions ofthe device therein, and the insulating strip also selves to closecut-away portions in the metallic housing adjacent the base. Themetallic stop member I6 has an upturned portion 23 terminating in a stopmember 24 adapted to engage either side of the stop 25 formed bypressing in a portion of the housing l2. This stop member I6 is alsoprovided with an upturned lug 23 adapted to transiently engage theoperating member 21 for driving the second unit.

In the form of construction shown, the second unit comprises a switchsubstantially similar to that shown in my copending application, SerialNo. 83,963, led June 6, 1936, and will not be described in detailherein. The switch is supported on an insulating base 28 which in turnis supported by a metallic housing member 29 secured to the end wall 33of the housing I2 of the rst unit. As best shown in Figure 4, the member29 in addition to the substantially cylindrical wall, comprises an outerface portion 33 which overlies the greater portion of the insulatingswitch base 28 and is cut away to give clearance to the terminals 31 and38. Thus the switch with the exception of the terminals, is enclosedwithin a metallic shield.

The member 29 is secured in place as shown by means of the lugs 3| whichpass through slots inthe wall 39 and are clinched over against the undersurface of the wall. The ends of the lugs 3l are turned inwardly whenclinchedso that they completely close any portionsl of the slots intheend wall 30 lying within the switch housing wall and thus insure animperforate xed metallic wall between the twor units.

The switch of the second unit comprises a pivot 32 which is securedthrough therbase 23 and also through the outer face portion 33 of themetallic wall member 29. The switch pivot is grounded by this connectionto the wallv 29. Upon this pivot 32 are carried the switch arm 34 vandalso the operating member 2'I. The spring 35 is connected between theoperating member 21 and the switch arm 34 and serves to drive the switcharm upon oscillation of the operating member 2l across the dead center,giving what is called a toggle or snap action to theswitch. The switcharm 34 drives a U- shapedvcontact member 36 into and out of engagementwith spaced xed contacts 52 and 53 connected to the solder lug terminals31 and 38. The operating member 2l is provided upon the supporting leg39 with the U-shaped portion 4I] which provides a double bearing for themember 2lv upon the pivot 32. The opposite arm 4I is provided with anenlarged cut-awai7 portion 42 which forms the spaced horns 43 and 44; Itwill be noted that the cut-away portion 42 is opposite the pivot 32 andthis portion is designed to afford clearance for a riveting tool used toupset the end 45 of the pivot 32.

As shown in Figure 1, the portion 39 of the operating member extendsoutwardly through an opening 46 formed in the housing wall 29 of thesecond unit or switch member. The portion 4I of the operating memberextends inwardli7 through an opening 41 formed in the lateral wall ofthe first unit housing I2. The switch arm 34 of the second unit ispreferably formed of insulating material so that the operating member 2lis not connected in or to the electrical .circuit passing through theswitch. As clearly shown in Figure 1, the operating member. 21 extendsoutwardly laterally of the two units at a point above the extendedportion 2| of the base II.v It also extends out only acomparativelyshort distance so that it does not engage the connecting lugs I9 and 20.

It will be seen that my improved construction comprises a structure withthe two control units enclosed in metal walls and with an imperforatewall located between the units. Adjacent slots are provided in thelateral walls of the unit housings for passage of means for jointlyoperating the devices. This joint operating means is formed of metal andis groundedV by connection to the housings so that it in itself servesas an additional shield. The parts are so designed that the slots in theunit walls are small and are to a large extent closed by the jointoperating means. Thus this means plays an important part in the totalshielding eiect. In certain forms of construction as shown, in order toreduce the overall size of the unit, the

I joint operating means may be located adjacent the terminals of thevariable resistance unit. In such cases this means is eilective inshielding the terminals of the variable resistance from the switch. Y

In operation of the device the resistance between the end terminals andthe center terminal I9 connected to the movable contact in theresistance unit or rst unit, is varied by rotating the shaft I4, andconsequentlyrotating the movable contact Il'. At the end of the movementin which the parts are shown, the second unit or switch is in the offposition.

Referring now to Figure 2, if the shaft I4 as seen in that iigure isrotated in a clockwise direction, the lug 26 will be pivoted in the samedirection and will engage the horn 43 of the member 2l. It will rotatethe member 2l in the counterclockwise direction about its pivot 32. Assoon asrthe spring 35 passes the dead center, the switch is snapped toon position by the force stored in this spring. As the shaft I4is'rotated further, the lug 23 may pass freely away from the member 2l.When the shaft I4 lis rotated toward its limit in the counterclockwisedirection, the lug 26 will engage the horn V44 of the member 2l and willmove that member in the clockwise direction to open the switch. Y f

It will be apparent that my construction affords la complete imperforatemetallic shield between the current-carrying portions of the rst unitand the current-carrying portions of the second unit., The metallic wall29 of the secondunit and the metallic housing I2 of the rst unit areconnected together electrically and mechanically, and both of thesemembers may be grounded in any suitable manner. The usual method AOigrounding is by connecting the housing I2 to the thimble I3 which is innormal use mounted upon a metallic chassis which serves as ground. Inthe form of construction shown, the grounding plate 48 is shown betweenthe base II and the metal washer 54 which is secured to the thimble I3and this plate has an upturned portion 49 through which passes one ofthe securing lugs 50 for the housing I2. This lug is bent over againstthe under face of the plate 48 and affords an effective groundingconnection.

The member 2l is not connected in or tothe electrical circuit in Aeitherunit, and this operating member is, therefore, what is called cold. Itis grounded at all times through the pivot 32 which is directlyconnected to the portion 33 ofV the switch housing wall 23. It effectsno transfer of energy from one unit to the other and therefore in no wayaiects the completev shielding between the units afforded by the endwall 33 ofthe housing I2. The connection between the units is simple andrequires no more parts than connections accomplished in the prior art byoperating members or cams which pass through the end walls of theadjacent units. While the shielding afforded with the switch camextending directly through perforations in the metal end wall isadequate for certain uses and requirements, it does not allord ascompletely effective shielding as that given by the imperforateshielding wall of the present construction. This connection does notincrease the effective size of the units since it extends out of thehousings above the extended portion 2l of the base, which is provided tocarry the terminals clear of the housing for connection to the wiresleading to other portions of the circuit.

Attention is directed 'to the fact that the stop carrying arm 23 and itsstop portion 24 travel in a plane located between the end wall 39 andthe leg 4| of the operating member 2. By virtue of this structuralrelationship, the stop arm 23 may be directed outwardly far enough tohave its outer end traverse an arc close to the side wall of the housingl2 from which the stationary stop 25 projects. Hence, the stop 25 can bequite short in a radial direction, which is desirable as it is thusstronger and easier to fabricate.

While I have shown certain preferred forms of construction, it will beapparent that the assembly is capable of modification and change to meetvarying conditions and requirements and I contemplate such variations ascome within the spirit and scope of the appended claims.

I claim:

l. In combination, two electrical control units arranged in tandem andeach having a substantially cylindrical housing with a metal side wall,a substantially unbroken metal partition wall separating and shieldingthe units from each other, a rotary shaft substantially coaxial with andprojecting from one unit and operable to actuate the instrumentalitiesthereof, the side walls of the housings having openings, an oscillatableoperating member for the other unit pivoted within the housing thereofand extending out through the opening in its side wall around thepartition wall and back in through the opening in the side wall of theiirst named unit, and means in the first named unit driven by its shaftfor actuating said operating member.

2. In combination, an electric snap switch of the type having a movablecontactor driven from one position to the other by a spring toggledevice, a substantially cup-shaped housing for the switch having a metalside wall provided with an opening, an operating member for the toggledevice pivoted within the housing of the switch and having a U-shapedpart projecting laterally through the opening in the housing side wallwith its inner leg in said opening and the outer leg spaced from theplane of the open end of said cup-shaped housing, an electrical controlunit of the type having rotary elements driven by a rotary shaft, asubstantially cup-shaped housing for said control unit having asubstantially unbroken metal end wall and having an opening in its sidewall, and means holding the switch and control unit assembled with theswitch housing having its open end closed by the metal end wall of thecontrol unit housing so that said end wall separates and shields theswitch from the control unit and is straddled by the legs of theU-shaped operating member with the outer leg entering the control unir,housing through the opening therein to Abe actuatable by the rotaryelements of the unit.

3. In combination, an electric snap switch, a switch housing having ametal side wall with an opening therein, an operating member for thesnap switch consisting of a .substantially U- shaped metal stamping, apivot post in the switch housing of the switch grounded to the metalside wall and having the operating member pivoted `thereon so that theoperating member is also grounded, the inner leg of the U-shapedoperating member extending laterally out through the opening in the sidewall of the switch housing so that its outer leg extends inwardly towardthe center of the switch, an electrical control unit of the type havingrotary elements driven by a rotary shaft, a housing for said controlunit having a metal side wall provided with an opening, a substantiallyunbroken metal partition wall providing an end wall common to bothhousings and separating and shielding the switch from the control unit,said partition wall being interposed between the legs of the U-shapedoperating member and the outer leg of the operating member entering thehousing of the control unit through the opening in its side wall, meansrotatable with the rotary elements of the control unit ladapted to havetransient engagement with the outer leg of the U-shaped operating memberinside the control unit housing, a stop arm rotatable with said rotaryelements of the control unit moving in a plane lying between said commonend wall of the housings and said outer leg of the operating member, anda stationary stop on the side wall of the control unit housingengageable by said stop arm.

4. In combination, two electrical control units, a housing for each unithaving a substantially cylindrical side wall, a substantially unbrokenmetal partition wall connected with the side walls of the two housingsso as to provide a common end wall for the two housings and an unbrokenelectrostatic shield between them, the side walls having openingsadjacent to each other at opposite sides of the partition wall, aU-shaped operating-member straddling the common end wall with the legsthereof passing through the side wall openings and its closed endoutside the housings, a pivoted support for the U-shaped operatingmember, a driving connection between the operating member and theinstrumentalities of one unit, a rotary shaft for driving theinstrumentalities of the other unit, and means driven by the shaft andoperable on the leg of the operating member inside the housing of thesecond designated unit for actuating the same so that both units arecontrolled from the one rotary shaft.

5. In a combined volume control and switch of the type intended for usewith radio apparatus, separate housings for the volume control unit andswitch unit, one of said housings having a substantially unbroken metalend wall, means for holding the housings assembled so that the two unitsare arranged in tandem with said substantially unbroken metal end wallforming an electrostatic shield therebetween, a base for one of saidunits constituting part of its housing and disposed substantiallyparallel to said end wall, a lateral extension on said base providing aterminal support, the housings of the two units having side walls, eachof which has an opening adjacent to said lateral extension o1' the base,a common operating shaft for the two units entering the housing of oneof the units, and an actuator for the other unit operable by the shaft,said actuator comprising a motion transmitting member having spacedarms, each entering one of the housings through its side wall openingwith its exposed portion overlying the lateral base extension.

6. In a combination radio control, a first unit having a base, asubstantially cup-shaped housing for said unit having its open endclosed by the base and having a substantially unbroken metal end walloverlying the base, said housing having an opening in its side wall, asecond unit, a substantially cup-shaped housing for said second unithaving at least its side wall of metal, a pivoted actuator for theinstrumentalities of the second unit, the metal side wall of the housingfor the second unit having an opening, means for holding the two unitsassembled with the second unit mounted on the outer face of thesubstantially unbroken metal end wall of the first unit, means on thepivoted actuator projecting out through the opening in the side wall ofthe housing of the second unit and back into the housing of the rst unitthrough the opening in its side wall, a common operating shaft for theAtvvo units entering the housing of the rst unit through the base todrive the movable elements of the rst unit, and means inside the housingof the first unit for transmitting driving force from the shaft to saidmeans on the pivoted member.

7. In combination, an electric snap switch unit of the type wherein amovable contactor is snapped yfrom one position to the other by a springtoggle device, a substantially cup-shaped switch housing having anopening in its side wall, a base in the bottom of the cup-shapedhousing, a pivot post carried by the base near'that portion of the sidewall having the opening, an operating member for the spring toggledevice of the snap switch unit, said operating member being pivoted onsaid post and having a U-shaped portion extending laterally from thepost with its inner leg disposed in said opening and its outer legdirected back over the pivot post but spaced therefrom and from theplane of the open end of the housing, a substantially unbroken metalwall closing the open end of the cupshaped housing and connected withthe side wall thereof to provide a shielding barrier, said wall beingstraddled by the legs of the U-shaped portion of the operating member sothat the outer leg thereof overlies the wall, an electrical control unitoperable in conjunction with the snap switch, means holding saidelectrical control unit assembled with the snap switch with the twounits arranged in tandem and the control unit disposed on the exteriorof said substantially unbroken metal Wall and Wholly Within the coniinesof its peripheral edge, said` control unit havingrotatable,instrumentalities, means on said rotatable instrumentaltiesadapted to have driving engagement with said outer leg 0f the U- shapedportion of the operating member, and a manually rotatable operatingmember for the rotatable instrumentalities of the control unit.

NEWTON C. SCHELLENGER.

